Photographic materials containing a chemical sensitizer



trite ees att 3,046,130 PHOTOGRAPHIC MATERIALS CONTAINING A CHEMICAL SENSITIZER Fritz Dersch and Millet R. De Angelus, Binghamton, N.Y., assignors to General Aniline & Film Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed May 12, 1960, Ser. No. 28,525 19 Claims. (Cl. 96-66) This invention relates to photographic materials. More particularly, this invention relates to photographic materials sensitized by means of water soluble heterocyclic compotmds which are substituted by a polyoxyalkylene chain.

It is well known that polyalkylene oxides such as polyoxyethylene and polyoxypropylene increase the speed of silver halide emulsions. It has also been observed that condensation products of alkylene oxides with amines, carboxylic acids, alcohols, amides or phenols (made according to U.S. Patents 1,970,578 and 2,213,- 477) and dicyclohexylol-dialkyl methane (see U.S. Patent 2,240,472) have been used as sensitizers. The polyalkylene oxides or the alkylene oxide condensation products should have a molecular weight of at least 300 and preferably 1,500 to 4,000 or more.

The use of the polyalkylene oxides or alkylene oxide condensation products as sensitizers is limited because of their tendency to increase the formation of fog during storage of the photographic film, especially storage at elevated temperature and high humidity. The use of conventioual antifoggants is not sufficient to satisfactorily eliminate or minimize fog formation in a film coated with an emulsion containing such products as sensitizers. Special antifoggants had to be found for use with such emulsions, and, in this connection, reference is made to U.S. Patents 2,704,716, 2,716,062 and 2,728,666.

It is an object of this invention to provide a novel seusitizer for use with a photographic emulsion or With a photographic developer to greatly increase the speed of the emulsion Without materially increasing the fogging tendency thereof, any tendency to fog being eliminated or minimized by the use of conventional autifoggants.

A further object of this invention is to provide a photographic film comprising a layer containing a water-soluble polyoxyalkylene derivative of a hydroXyor mercaptosubstituted azole in which the polyoxyalkylene chain replaces the hydrogen atom of the mercapto group.

Other objects and advantages of this invention Will appear to those skilled in the art from the detailed description thereof given below.

We have now discovered that Water-soluble oxyalkylene and polyoxyalkylene derivatives of Z-mercapto or 2-hydroxy-substituted azoles, namely, condensation products of alkylene oxide, e.g., ethylene oxide or propylene oxide, epichlorhydrine, trimethylene chlorhydriue or glycerol oz-chlorhydrine with a Z-hydroxyor Z-mercapto-substituted azole, e.g., benzothiazole, benzoxazole, benzimidazole or quinoline, have a remarkable speed increasing effect on silver halide emulsions. Surprisingly, these reaction products, unlike the heretofore used polyoxyalkylcues, do not have the objectionable tendency of increasing the fog of photographic films during storage especially under conditions of high temperature and high humidity.-

The fogging of photographic film having a coating of a silver halide emulsion and containing the novel sensitizer of our invention may, therefore, be controlled by the use of the conventional antifoggants and stabilizer used in the photographic art; and the use of a special type of antifoggant to prevent fogging of an emulsion containing conventional polyoxyalkylenes such as those disclosed in U.S. Patents 2,704,716, 2,716,062 and 2,728,666 becomes unnecessary.

. The polyoxyalkylene substituted heterocyclic compounds contemplated for use herein have the following general formula:

2-polyoxyethyleneoxybenzothiazole S 2-polyoxyethyleuemercaptobeuzothiarzole 2-polyoxyethylenemercaptoquinoliue NH 2-polyoxyethyleuepropyleneoxyrnercaptobeuzimidazole These heterocyclic polyoxyalkylene compounds are produced by introducing hydroxy aliphatic ether radlcals into 2hydroxyor Z-mercapto-substituted azoles according to the procedure described in United States Patent act . a t The above described heterocyclic compounds are condensed with hydroxy compounds such as ethylene oxide,

propylene oxide, epichlorhydrine, trimethylene chlorhydrine, glycerol a-chlorhydrine, glycol, glycerine, polyglycerine and the like. In some instances, two or more of these compounds are reacted consecutively with the mercaptoor hydroxy-substituted azole. Alkaline reacting compounds such as sodium or potassium hydroxide or heavy metal salts such as nickel sulfate serve as catalyzing agents.

The increase of effective sensitivity of photographic silver halide emulsions with the polyoxyalkylene derivatives of the Z-mercaptoor 2hydroxy-substituted heterocyclics can be obtained in a number of ways. They may be added to an undercoating, to a middle coating, to an overcoating or to a surface coating prior to the coating operation. If desired, they may be added during the actual preparation of the emulsion, either before or after washing of the emulsion.

The speed and sensitivity increasing agents of our invention may be used in various types of photographic emulsions; e.g., nonsensitized emulsions, orthochromatic,

' panchromatic, and X-ray emulsions. If used with sensitizing dyes, they may be added to the emulsion before or after the dyes are added. Various silver salts may be used as a sensitive element, such as silver bromide, silver iodide, silver chloride or mixed silver halides. These hydroxy-substituted ether or thioether derivatives of heterocyclic compounds may be used in emulsions intended for color photography, e.g., emulsions containing color-forming components. The carrier in the photographic emulsion may be gelatin or other colloids such as collodion, albumen, cellulose derivatives, polyvinyl alcohol or synthetic resins. The emulsion containing our novel sensitizer may be coated on any conventional base, such as paper, glass, cellulose ester such as cellulose acetate, cellulose ethers and others.

The amounts of sensitivity increasing agents used per kilogram of emulsion range from 15 to 500 milligrams per kilogram of liquid emulsion. When expressed in terms of silver halide, the amounts of sensitivity increas ing agents range from 25 to 500 milligrams per mole of silver halide.

The sensitivity increasing agents of our invention can also be added to pre-bath solutions or to standard developer solutions. These developer solutions contain, in addition to the speed increasing agent, a developing agent such as metol, hydroquinone l-phenyl 3 pyrazolidone (phenidone); an alkali such as sodium or potassium carbonate; a preservative or anti-oxidant such as sodium sulfite; and an antifoggant such as potassium bromide. The amounts of speed increasing agents used range from 0.3 to 6.0 grams per liter of developer solution.

The following specific examples are given of the manner of producing and using the sensitizers of our invention. It is to be understood, however, that these examples are given by Way of illustration and not by way of limitation.

Example I s i G-S-QHzCI-Ia-(CHiCH9O) 1-I \NH A silver halide emulsion in gealtin containing 4 percent silver iodide and 96 percent silver bromide was prepared in a conventional manner and brought up to its maximum light sensitivity. It was then readied for coating on film base, that is, melted at 40 C.; and the necessary coating finals were added, such as sensitizing dyes, stabilizers and hardeners. A percent aqueous solution of the reaction product of Z-mercaptobenzimidazole and 6 moles of ethylene oxide was prepare, and 10 cc. of this solution were added to a sample of the above described also Grams Meto-l (p-inethylaminophenol sulfate) 1.5 Sodium sulfite, anhydrous 45.0 Sodium bisulfite 1.0 Hydroquinone 3.0 Sodium carbonate, monohydrated 6.8 Potassium bromide .8

Water to make 1.0 liter.

The developed films were short-stopped, fixed and washed in the conventional manner. The results ob tained were as follows:

The ethylene oxide derivative of Z-mercaptobenzimidazole which served as a sensitizer was prepared as follows: 50 grams of Z-mercaptobenzimidazole was mixed with 0.5 gram of potassium hydroxide which had been dissolved in a minimum amount oi: water; the mass was heated to C.; ethylene oxide was passed through until 6 moles of ethylene oxide had been taken up.

The procedure was the same as in Example I excepting that there was used the reaction product of Z-mercaptobenzimidazole and trimethylene chlorhydrine which was then condensed with 8 moles of ethylene oxide. The results were similar to those obtained in Example I.

This addition product was prepared as described in Example VI of United States Patent 2,642,430.

Example III a tea Pg The procedure was the same as in Example I excepe ing that the reaction product of 2-hydroxybenzothiazole and 4 moles of propylene oxide iodide was used. The results were similar to those obtained in Example I.

The compound was prepared by heating under reflux 1 mole of 2-hydroxybenzothiazole and 1 mole of propylene oxide for 1 hour using a small amount of potassium hydroxide. Additional increments of propylene oxide were added while heating and refluxing continued until a total of 4 moles of propylene oxide had been consumed.

Example V One kilo of a silver halide emulsion in gelatin containing 4 percent silver iodide and 96 percent silver bromide was coated on film base in a manner known to the art. After the coating was performed, an aqueous gelatin solution containing 20 grams of gelatin per liter and 20 milligrams of the polyoxyethylene derivative of 2-mercaptobenzimidazole of Example I was coated thereon as an anti-abrasion layer. After drying, film samples were exposed and processed as described in Example I. The samples described exhibited a relative speed of 150 with a fog of .22 as compared with a type coating of the same emulsion having an anti-abrasion layer similar to that described above, but lacking the speed increasing additive and having a speed of 100 and a fog of .20.

Example Vl Several samples of a conventional photographic film were exposed in a type II-B sensitometer and then divided into two groups. One group of samples was developed for twelve minutes at 68 F. in a standard metolhydroquinone developer as described in Example I. The other group of samples was developed for the same length of time and at the same temperature as the first group in a metol-hydroquinone developer which had been prepared by adding to 1 liter of the developer described in Example I, 2 grams of the reaction product of ethylene oxide and Z-mercaptobenzimidazole. It was found that the samples developed in the standard developer had a relative speed of 100 whereas the samples developed in the developer containing the novel sensitivity increasing agent of our invention showed a relative speed of 175 without an increase in fog. Modifications of the invention will occur to persons skilled in the art. Thus, it is evident that in lieu of the ethylene oxide addition products of the examples, any of the addition products mentioned above may be em ployed in our invention. We, therefore, do not intend to be limited in the patent granted except as necessitated by the appended claims.

We claim: 7

1. A light-sensitive silver halide emulsion containing as a sensitizer therefor, a water soluble heterocyclic polyoxyalkylene compound selected from the group consisting of those having the following general formula:

wherein A is a member selected from the group consisting of oxygen and sulfur; R and R are alkylene groups containing from 2 to 3 carbon atoms; X represents the atoms necessary to complete a heterocyclic mononuclear ring and is a member selected from the group consisting of oxygen, sulfur, imino and vinylene; Z represents the atoms necessary to complete an aromatic ring system of the benzeneand naphthalene series; and n is an integer between 4 and 40.

2. A light-sensitive silver halide emulsion containing as a sensitizer therefor, a compound of the following formula:

\I/ SCH2CHzO(CHzCHz0) H wherein n is an integer between 4 and 40.

4. A photographic material comprising a base and a gelatino silver halide emulsion layer containing as a sensitizer therefor, a water soluble heterocyclic polyoxyalkylene compound of the following formula:

wherein A is a member selected from the group consisting of oxygen and sulfur; R and R are alkylene groups containing from 2 to 3 carbon atoms; X represents the atoms necessary to complete a heterocyclic mononuclear ring and is a member selected from the group consisting of oxygen, sulfur, imino, vinylene; and Z represents the atoms necessary to complete an aromatic ring system of the benzene and naphthalene series; and n is an integer between 4 and 40.

5. A photographic material comprising a base and a light-sensitive silver halide emulsion layer containing as a sensitizer therefor, a compound of the following formula:

wherein n is an integer between 4 and 40.

6. A photographic material comprising a base and a light-sensitive silver halide emulsion layer containing as a sensitizer therefor, a compound of the following formula:

wherein n is an integer between 4 and 40.

8. The process of increasing the sensitivity of a lightsensitive silver halide material comprising a base having a light-sensitive silver halide emulsion thereon which spaeaso z: o-A-rnO-ononon wherein A is a member selected from the group consisting of oxygen and sulfur; R and R are alltylene groups containing from 2 to 3 carbon atoms; X represents the atoms necessary to complete a heterocyclic mononuclear ring and is a member selected from the group consisting of oxygen, sulfur, imino and vinylene; Z represents the atoms necessary to complete an aromatic ring system of the benzene and naphthalene series; and n is an integer between 4 and 40.

9. The process of increasing the sensitivity of a lightsensitive silver halide material comprising a base having a light-sensitive silver halide emulsion thereon, whicn comprises exposing said emulsion and developing the same in the presence of a compound having the following formula:

GSCH2CH2O(OHzOI-IZO)HH wherein n is an integer between 4 and 40.

10. The process of increasing the sensitivity of a lightsensitive silver halide material comprising a base having a light-sensitive silver halide emulsion thereon, which comprises exposing said emulsion and developing the same in the presence of a compound having the following formula:

\I/S-CI{QCIIZO-(CHZCHZO)X1H wherein n is an integer between 4 and 40.

ll. The process of increasing the sensitivity of a lightsensitive silver halide material comprising a base having a light-sensitive silver halide emulsion thereon, which comprises exposing said emulsion and developing the same in the presence of a compound having the following formula:

wherein A is a member selected from the group consisting of oxygen and sulfur; R and R are alkylene groups containing from 2 to 3 carbon atoms; X represents the atoms necessary to complete a heterocyclic mononuclear ring and is a member selected from the group consisting of oxygen, sulfur, imino and vinylene; Z represents the 8 atoms necessary to complete an aromatic ring system of the benzene and naphthalene series; and n is an integer between 4 and 4O.

13. A photographic developer solution comprising a silver halide developing agent, an alkali, an anti-oxidant, an antifoggant, and containing as a speed increasing agent a compound of the following formula:

wherein n is an integer between 4 and 40.

14. A photographic developer solution comprising a silver halide developing agent, an alkali, an anti-oxidant, an antifoggant, and containing as a speed increasing agent a compound of the following formula:

wherein n is an integer between 4 and 40.

15. A photographic developer solution comprising a silver halide developing agent, an alkali, an anti-oxidant, an 'antifoggant, and containing as a speed increasing agent a compound of the following formula:

wherein n is an integer between 4 and 40.

16. A photographic material comprising a base having a layer of a light-sensitive silver halide emulsion thereon, said silver halide layer being in contiguous contact with another layer comprising a colloidal carrier and a watersoluble heterocyclic polyoxy-alkylene compound selected from the group consisting of those having the following general formula:

wherein A is a member selected from the group consisting of oxygen and sulfur; R and R are alkylene groups containing from 2 to 3 carbon atoms; X represents the atoms necessary to complete a heterocyclic mononuclear ring and is a member selected from the group consisting of oxygen, sulfur, imino and vinylene; Z represents the atoms necessary to complete an aromatic ring system of the benzene and naphthalene series and n is an integer between 4 and 40.

17. A photographic material comprising a base having a layer of a light-sensitive silver halide emulsion thereon, said silver halide being in contiguous contact with another layer comprising a colloidal carrier and a cornpou-nd of the following formula:

wherein n is an integer between 4 and 40.

18. A photographic material comprising a base having a layer of a light-sensitive silver halide emulsion thereon, said silver halide being in contiguous contact with another layer comprising a colloidal carrier and a compound of the following formula:

wherein n is an integer between 4 and 40.

19. A photographic material comprising a base having a layer of a light-sensitive silver halide emulsion thereon, said silver halide being in contiguous contact with another layer comprising a colloidal carrier and a compound of the following formula:

References Cited in the file of this patent UNITED STATES PATENTS 2,944,902 Carroll et al July 12, 1960 

12. A PHOTOGRAPHIC DEVELOPER SOLUTION COMPRISING A SILVER HALIDE DEVELOPING AGENT, AN ALKALI, AN ANTI-OXIDANT AND AN ANTIFOGGANT CONTAINING AS A SPEED INCREASING AGENT A WATER-SOLUBLE HETEROCYCLIC POLYOXYALKYLENE COMPOUND SELECTED FROM THE GROUP CONSISTING OF THOSE HAVING THE FOLLOWING GENERAL FORMULA: 